1. Field of the Invention
The present invention relates to an image display device, and more particularly to a planar image display device which can suppress a malfunction of a driver attributed to the elevation of temperature.
2. Description of the Related Art
As a planar image display device, a liquid crystal display device, a plasma display device or an organic EL display device has been well-known. In addition to these display devices, display devices which adopt various other display methods have been put into practice, have been studied or are on their way to practical use. With respect to driving of these image display devices, the explanation is made hereinafter by taking the liquid crystal display device as an example. In general, the liquid crystal display device is constituted of a liquid crystal display module formed by assembling a printed circuit board such as a display control circuit, a backlight, and a power source printed circuit board of the backlight to a liquid crystal panel (hereinafter, also referred to as a liquid crystal panel or a panel simply), and a casing which houses the liquid crystal display module therein. The liquid crystal panel is constituted of two insulation substrates basically made of glass and liquid crystal sealed therebetween, wherein the liquid crystal forms a display region constituted of a large number of pixel arrays. As a typical example of an active-matrix-type liquid crystal panel popularly used in the display device, there has been known a so-called TN-type liquid crystal panel which mounts thin film transistors (TFT) constituting pixel circuits and various lines on one substrate and mounts color filters and a common electrode on another substrate, or a so-called IPS-type liquid crystal panel which mounts pixel electrodes and counter electrodes on one substrate. Further, on a periphery of the substrate constituting such a liquid crystal panel, a source driver for supplying display signals to the pixels and a gate driver for scanning the pixel arrays are mounted.
Along with the realization of an image display device with high definition or with super-high definition in recent years, a drive frequency at which a display signal is supplied to a large number of pixels formed on a panel rises and hence, self-heating of a source driver becomes too large to be ignored. Some image display devices adopt the front-surface closed structure which mounts an acrylic plate on a front surface of the panel. In such image display devices, heat generated by the panel itself is increased. When the image display device is a liquid crystal display device, an environmental temperature of the panel rises due to the radiation of heat from a backlight of the liquid crystal display device or the like and hence, there exists a possibility that a temperature of the source driver exceeds a use-limit temperature. Under such circumstances, it is urgently necessary to take measures to cope with the radiation of heat from drivers of the panel including the source driver.
As documents which disclose the related art relating to such measures to cope with the heat radiation, Japanese patent No. 3656455 (patent document 1) and JP-A-2000-268735 (patent document 2) are named. Patent document 1 discloses the heat radiation structure of an IC chip mounted on a flexible printed circuit board (FPC) on which a wiring pattern is formed, wherein a heat radiation body formed of an aluminum plate or the like is adhered to a back surface of the IC chip (a surface of the IC chip on a side opposite to the FPC). Further, patent document 2 discloses the heat radiation structure of an IC chip in which an FPC which mounts a driver thereon by way of a heat-radiation-use conductive pattern is fixed to a substrate of a panel.